The overall objective of this proposal is to develop photocrosslinkable hydrogel networks for tissue engineering that elicit desired properties for the repair or replacement of craniofacial cartilage. From a clinical perspective, we hypothesize that the treatment of cartilage defects can be greatly improved by developing injectable polymer-cell constructs that can be reacted upon exposure to light to form well-adhered hydrogels of the exact dimensions and shape of the defect. From a fundamental perspective, we hypothesize that bioinspired hydrogels will provide an improved cell matrix for three-dimensional tissue engineering when the gels are engineered to 1) degrade at a rate that matches tissue formation, 2) incorporate critical cell signals and growth factors, and 3) allow easy structural and chemical modification through photopatterning. In the proposed research plan, we aim to Aim 1: identify and investigate important hydrogel properties that influence the production, composition, and distribution of extracellular matrix in cartilage tissue engineering constructs. Aim 2: develop the next generation of hydrogel matrices through advanced photopatterning techniques, to accelerate tissue formation and address critical issues that limit the engineering of thick, three-dimensional cartilaginous tissue. Aim 3: examine important clinical issues that are critical to the ultimate repair of structural and craniofacial cartilage deficiencies, namely the integration of tissue engineered and native cartilage, adhesion of in situ formed constructs to native cartilage, and the engineering of complex three-dimensional tissue constructs.